Paper output mechanism

ABSTRACT

A paper output mechanism includes: a roller pair composed of a first roller and a second roller travelable around the first roller and configured, when the second roller is in a first position, to output a piece of paper to a paper placement part by pinching the piece of paper between the first and second rollers and driving at least one of the first and second rollers into rotation with an actuator; and a roller position changing mechanism for switching the second roller between the first position and a second position located closer to the paper output side than the first position. When the trailing edge of the piece of paper is sent out to the paper placement part, the roller position changing mechanism changes the second roller from the first position to the second position.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority under 35 USC 119 to Japanese PatentApplication No. 2008-018213 filed on Jan. 29, 2008, the entire contentsof which are incorporated herein by reference.

BACKGROUND

The techniques disclosed in this specification relate to paper outputmechanisms for outputting a piece of paper conveyed to the terminal endof a paper conveyance path from the terminal end thereof to a paperplacement part disposed below the terminal end.

It is so far well known that in printers such as for photo printingsystems their printer body is internally provided with a paperconveyance path along which paper is conveyed. The terminal end of thepaper conveyance path is located in the vicinity of a paper output portin the printer body. A piece of paper (printed piece of paper) conveyedto the terminal end of the paper conveyance path is output from theterminal end through the paper output port by a paper output mechanism,such as a roller pair, disposed at the terminal end.

Disposed outside the printer body and near the paper output port is apaper placement part, made such as of a tray or a belt of a beltconveyer, for receiving output pieces of paper and placing them thereon.If the paper placement part is a belt conveyer, the printer isconfigured to convey pieces of paper placed on the belt of the beltconveyer in the direction orthogonal to the paper output direction andcollect them for each print order (see, for example, Published JapanesePatent Application No. 2001-83684).

SUMMARY OF THE DISCLOSURE

The paper placement part is generally disposed below the terminal end ofthe paper conveyance path, whereby the leading end of each piece ofpaper sent out from the terminal end towards the paper placement partsags by gravity and is output while sliding on the top surface of thepaper placement part or the top surface of a piece of paper alreadyplaced on it. Therefore, after the trailing edge of the piece of paperis sent out, the paper stop point is not fixed owing to the frictionalresistance acting on the leading edge thereof and the paper placementpoint varies with each output piece of paper. In particular, when a longrolled paper web is cut in a given length of piece and then output, thelong paper web is normally rolled with the printing surface to beprinted coming outside and the printed and cut piece of paper is outputwith the printed surface facing up. Therefore, the output piece of paperhas a curl with the lengthwise middle thereof rising up from both endsthereof owing to a core set of the paper web rolled around a core. Thisincreases variations in the paper placement point. If the paperplacement point varies in this manner, this increases the likelihoodthat, particularly when pieces of paper are conveyed by a belt conveyerto transfer them such as to a collection part, the transfer isdisrupted.

To cope with the above problem, if the output speed of the piece ofpaper is increased to some degree, the paper stop point, i.e., the paperplacement point, can be stabilized.

However, for example, if a dryer for drying ink adhering to the printingsurface of paper is disposed in the interior of the printer body in thevicinity of the paper output port, the output speed of the piece ofpaper must be reduced in order to certainly dry the ink. In this case,it is difficult to increase the output speed of the piece of paper.

The present invention has been made in view of the foregoing points and,therefore, an object of the invention is to provide a paper outputmechanism that can stabilize the paper placement point on the paperplacement part even if it is difficult to increase the output speed ofthe piece of paper.

To attain the above object, what is provided is a paper outputmechanism, disposed at the terminal end of a paper conveyance path, foroutputting a piece of paper conveyed to the terminal end of the paperconveyance path from the terminal end thereof to a paper placement partdisposed below the terminal end of the paper conveyance path. The paperoutput mechanism includes: a roller pair composed of a first roller anda second roller travelable around the first roller and configured, whenthe second roller is in a first position on a traveling path of thesecond roller, to output the piece of paper to the paper placement partby pinching the piece of paper between the first and second rollers anddriving at least one of the first and second rollers into rotation withan actuator; and a roller position changing mechanism for switching thesecond roller between the first position and a second position locatedon the traveling path of the second roller and closer to the paperoutput side than the first position, wherein the roller positionchanging mechanism is configured, when the first roller and the secondroller in the first position send out the trailing edge of the piece ofpaper to the paper placement part in the course of output of the pieceof paper to the paper placement part, to change the second roller fromthe first position to the second position.

With the above configuration, in sending out the trailing edge of eachpiece of paper to the paper placement part, the second roller moves fromthe first position to the second position. Therefore, in conjunctionwith the movement of the second roller, a force in the paper outputdirection is applied from the second roller to the trailing edge of thepiece of paper, whereby the piece of paper is accelerated in the paperoutput direction. Thus, after the trailing edge is sent out, the pieceof paper can easily move against the frictional force acting on theleading edge thereof. Therefore, even if the output speed of the pieceof paper is low in sending out part thereof other than the trailingedge, the output speed is increased in sending out the trailing edgethereof, whereby the paper placement point on the paper placement partcan be stabilized. Furthermore, since the output speed of the piece ofpaper is decreased in sending out the part thereof other than thetrailing edge, ink adhering to the printing surface of the piece ofpaper, for example, can be certainly dried.

Preferably, the first position is a position in which the axis ofrotation of the first roller is located closer to the paper output sidethan the axis of rotation of the second roller and the second positionis a position in which the axis of rotation of the second roller islocated closer to the paper output side than the axis of rotation of thefirst roller and the pinch of the piece of paper between the first andsecond rollers is released.

Thus, the traveling stroke of the second roller from the first positionto the second position can be increased to increase the output speed ofthe trailing edge of the piece of paper as much as possible.Furthermore, when the second roller is in the first position, if thepiece of paper has a curl due to a core set formed by rolling a paperweb around a core, the first and second rollers can easily correct thecurl of the piece of paper (decurl the piece of paper), which furtherstabilizes the paper placement point on the paper placement part. On theother hand, when the second roller is in the second position, the pinchof the piece of paper is released, whereby the next piece of paper cansmoothly enter between the first and second rollers. This prevents theleading edge of the next piece of paper from lodging on the first orsecond roller.

When the first roller and the second roller in the first position sendout the trailing edge of the piece of paper to the paper placement partin the course of output of the piece of paper to the paper placementpart, the rotational driving speed of the roller driven into rotation bythe actuator is preferably changed to higher side.

Thus, coupled with change of the second roller from the first positionto the second position, the piece of paper can be further accelerated inthe paper output direction. This further stabilizes the paper placementpoint on the paper placement part.

The roller pair is preferably disposed at the terminal end of the paperconveyance path provided in a printer body and in the vicinity of apaper output port in the printer body.

This provides an optimum paper output mechanism for a printer in a photoprinting system handling curled pieces of paper.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view showing the appearance of an inkjet printerincluding a decurling unit as a paper output mechanism according to afirst example embodiment.

FIG. 2 is a perspective view showing the structure of the inkjet printerinside a housing.

FIG. 3 is a plan view showing the structure of the inkjet printer insidethe housing.

FIG. 4 is a front view showing the structure of the inkjet printerinside the housing.

FIG. 5 is a schematic diagram of the inkjet printer when viewed from theleft of the housing, showing a conveyance path of printing paper.

FIG. 6 is a cross-sectional view showing the structure of a drying unitand the decurling unit when viewed from the left of the housing.

FIG. 7 is a perspective view showing the structure of the inkjet printeraround a paper output port when viewed from the front of the housing.

FIG. 8 is a front view showing the structure of the inkjet printeraround the paper output port when viewed from the front of the housing.

FIG. 9 is a side view of the decurling unit when a decurling roller ispositioned in a pinch release position.

FIG. 10 is a side view of the decurling unit when the decurling rolleris positioned in a conveyance position.

FIG. 11 is a side view of the decurling unit when the decurling rolleris positioned in a decurling position.

FIG. 12 is a perspective view showing the structure of an inkjet printerincluding a decurling unit according to a second example embodiment.

FIG. 13 is a plan view showing the structure of the inkjet printeraccording to the second example embodiment.

DETAILED DESCRIPTION

A description is given below of example embodiments with reference tothe drawings. The following example embodiments are merely illustrativein nature and are not intended to limit the scope, applications and useof the invention.

First Example Embodiment

FIG. 1 shows the appearance of an inkjet printer A including a decurlingunit as a paper output mechanism according to a first exampleembodiment, and FIGS. 2 to 5 show the internal structure of the inkjetprinter A. The inkjet printer A is used for a photographic printingsystem and, for example, used for printing photographic images onprinting paper P1 or P2 based on image data transmitted via acommunication cable from a reception block for obtaining the image dataand correcting it as necessary. More specifically, the inkjet printer Ais configured to be capable of performing an automatic printing forpulling out one end of a long roll of printing paper P2 and printing animage on the printing surface of the roll of printing paper P2(hereinafter, referred to as a paper web P2) and a manual-feed printingfor printing an image on the printing surface of a sheet of printingpaper P1 (hereinafter, referred to as a paper sheet P1) previously cutin a given size.

When in the following description the paper sheet P1 and the paper webP2 need not be particularly distinguished, they are referred to asprinting paper P1 or P2. Furthermore, the printing surface means thesurface on which an image is to be printed. The printing surface of eachpaper sheet P1 is determined when the paper sheet P1 is set on amanual-feed tray 7 (see FIG. 5). Specifically, the printing surface isthe side of the paper sheet P1 facing upward when the paper sheet P1 isset on the manual-feed tray 7. On the other hand, the printing surfaceof the paper web P2 is the side thereof facing radially outward when thepaper web P2 is rolled.

—General Structure—

As shown in FIGS. 1 to 5, the inkjet printer A includes a printer body90, a manual-feed tray 7 for manually setting a paper sheet P1 thereonand feeding it therefrom into the printer body 90, and a paper outputtray 5 serving as a paper placement part for receiving pieces ofprinting paper P1 or P2 output from the printer body 90 and placing themthereon.

The printer body 90 includes: a housing 6; a paper roll containing part1 disposed in a lower part of the interior of the housing 6 andcontaining a paper web P2 rolled with its printing surface outside; aprinting part 2 (see FIGS. 2 and 5), disposed in an upper part of theinterior of the housing 6 (above the paper roll containing part 1), forprinting based on image data an image on the printing surface of thepaper sheet P1 fed from the manual-feed tray 7 or the printing surfaceof the paper web P2 pulled out of the paper roll containing part 1; inkstorages 3, located in the lower part of the interior of the housing 6on both sides of the paper roll containing part 1, for storing ink to besupplied to the printing part 2; and a roller unit 200, disposed on anupper part of a cover member 95 attached to the housing 6 to be freelyopened and closed, for conveying and feeding a paper sheet P1 set on themanual-feed tray 7 towards the printing part 2 when the cover member 95is closed.

Disposed in the upper part of the housing 6 and downstream of theprinting part 2 in the direction of paper conveyance are a roller cutter41 for cutting out an unnecessary part of printed printing paper P1 orP2, a back printing unit 4 for printing a serial number on the back sideof each piece of printing paper P1 or P2, a drying unit U6 for dryingthe piece of printing paper P1 or P2 printed in the printing part 2, apaper output unit U4 for conveying the piece of printing paper P1 or P2printed in the printing part 2 further downstream; and a decurling unitU7 for performing a decurling process of correcting the curl of thepaper web P2 that is a core set formed by rolling the paper web P2around the core. Disposed downstream of the decurling unit U7 in thedirection of paper conveyance is the paper output tray 5, extendingoutside from a paper output port 47 in the housing 6, for receivingpieces of printing paper P1 or P2 delivered by the decurling unit U7 andplacing them thereon.

Hereinafter, the side of the housing 6 towards the paper output tray 5(“output side” shown in FIG. 3) is referred to as the housing frontside, the side thereof opposite to the paper output tray 5 (“feedingside” shown in FIG. 3) is referred to as the housing rear side, the leftside thereof as viewed from the housing front side is referred to as thehousing left side, and the right side thereof as viewed from the housingfront side is referred to as the housing right side. Therefore, theright-to-left direction in FIG. 5 is the housing front-to-rear directionand the direction orthogonal to the drawing sheet of FIG. 5 is thehousing right-to-left direction. The housing right-to-left directioncoincides with the width direction of the paper sheet P1 set on and fedfrom the manual-feed tray 7 and the width direction of the paper web P2contained in and fed from the paper roll containing part 1.

—Paper Conveyance Mechanism—

As shown in FIG. 5, the inkjet printer A is provided with a paperconveyance mechanism for pulling the leading edge of a paper web P2 outof the paper roll containing part 1 and conveying it along a given paperconveyance path. To form the paper conveyance path, the paper conveyancemechanism includes, in order from the feed unit U1 for feeding a paperweb P2, the feed unit U1, a printing unit U2, a cutter unit U3, thedrying unit U6, the paper output unit U4 and the decurling unit U7.Thus, image data is printed on the printing surface of the printingpaper P1 or P2 located on the paper conveyance path in the printing unitU2 provided in the printing part 2.

In this first example embodiment, for another paper feed path other thanthe feed path of a paper web P2 from the feed unit U1 to the printingunit U2, the paper conveyance mechanism further includes a manual-feedunit U5 configured to pull in a paper sheet P1 from the manual-feed tray7 and feed it to the printing part 2.

The paper conveyance mechanism is configured so that, in printing on apaper web P2, the feed unit U1 feeds the paper web P2 set in the paperroll containing part 1 to the printing unit U2, the printing unit U2then prints image data on the fed paper web P2 with the print head Hwhile conveying the paper web P2. Then, the paper conveyance mechanismcoveys the printed paper web P2 to the cutter unit U3, the cutter unitU3 cuts the paper web P2 in a given print size, the drying unit U6 thendries the cut piece of paper web P2, and the paper conveyance mechanismconveys the cut piece of paper web P2 out to the paper output tray 5while the decurling unit U7 decurls the cut piece of paper web P2.Hereinafter, the upstream side and downstream side in the direction ofconveyance of the paper web P2 being conveyed during printing isreferred to simply as the upstream side and downstream side,respectively.

The feed unit U1 includes a core roller 21 for winding a paper web P2 ina roll thereon to contain the rolled paper web P2 in the paper rollcontaining part 1, a transverse restriction roller 22 for restrictingthe transverse position of the paper web P2 pulled out of the coreroller 21, a conveyance drive roller 24 capable of being driven intorotation by an unshown electric motor to convey the paper web P2, andtwo pinch rollers 25 opposed to the conveyance drive roller 24 andengageable against the conveyance drive roller 24 to pinch the paper webP2 together with the conveyance drive roller 24.

The feed unit U1 is configured to pull the paper web P2 out of the paperroll containing part 1 and also feed it to the printing part 2 by therotation of the conveyance drive roller 24.

The conveyance drive roller 24 is configured to be rotated forward by anunshown electric motor to pull the paper web P2 out of the paper rollcontaining part 1 and feed it to the printing part 2 and rotatedbackward by the electric motor to return the paper web P2 to the paperroll containing part 1.

Thus, the inkjet printer A can cut off the printed part of the paper webP2 into a given size by the cutter unit U3 downstream of the printingpart 2, then return the remaining paper web P2 after the cuttingupstream and restart printing with the leading edge of the remainingpaper web P2 or can return the paper web P2 after the cutting into thepaper roll containing part 1, feed a paper sheet P1 to the printing part2 through the manual-feed unit U5 and print on it. Furthermore, inreplacing the paper web P2 with new one, part of the paper web P2 pulledout of the paper roll containing part 1 can be returned into the paperroll containing part 1.

The printing unit U2 includes: the print head H for ejecting ink to theprinting paper P1 or P2 and forming an image on it; a paper holder D forholding by suction the printing paper P1 or P2 at a position allowingprinting of the print head H; and a pair of paper conveyance rollers 33disposed downstream of the paper holder D and engaged against eachother. The conveyance drive roller 24 and the pinch rollers 25 in thefeed unit U1 are used also as components of the printing unit U2 and actto convey the printing paper P1 or P2 in the printing unit U2.

The print head H is configured to be movable along a rail 30 extendingin a main scanning direction X (see FIG. 3) coinciding with the widthdirection of the printing paper P1 or P2 (i.e., the housingright-to-left direction). Specifically, when the rotational force of adrive motor 32 is transmitted through a pulley to a drive belt 31, theprint head H moves in the main scanning direction X according to theamount of rotation of the drive belt 31.

The print head H further includes two head units 38 and 38 (see FIG. 5)arranged along a sub-scanning direction Y (see FIG. 3) orthogonal to themain scanning direction X and coinciding with the direction of travel ofthe printing paper P1 or P2 (i.e., the housing front-to-rear direction).The print head H is configured to print a given image or characters onthe printing paper P1 or P2 by ejecting ink through ink-jet nozzles (notshown) formed in these two head units 38 and 38.

The printing paper P1 or P2 is intermittently (stepwise) conveyed incertain unit amounts of conveyance in the sub-scanning direction Y bythe conveyance drive roller 24, the pinch rollers 25 and the paperconveyance rollers 33. During each stopping time of the printing paperP1 or P2 in the course of intermittent conveyance, the print head Hscans one way (makes a forward scanning or a backward scanning) in themain scanning direction X. During the scanning, ink is concurrentlyejected through the ink-jet nozzles of each head unit 38 to the printingsurface (top surface) of the printing paper P1 or P2. In other words,after a single scanning of the print head H, the printing paper P1 or P2is conveyed by a unit amount of conveyance and the print head H thenscans once. By repeating this operation, a desired image is printed.

The ink storages 3 include their respective box-shaped cases 61 (seeFIG. 4) disposed on the right and left of the inkjet printer A. Thesecases 61 contain seven removable ink cartridges in total (in FIG. 4,three in the left case 61 and four in the right case 61). The inkcartridges 62 are charged with different types of ink having differenthues. Therefore, the ink cartridges 62 spent or being used can bereplaced with new ones by removing them from the cases 61 and settingnew ones in the cases 61. Seven types of ink charged in these inkcartridges 62 are yellow (Y), magenta (M), cyan (C), black (K), red (R),violet (V) and clear (CL).

The cutter unit U3 includes a roller cutter 41 and is configured to cutthe printing paper P1 or P2 into a given size (length) by moving theroller cutter 41 in the width direction at an appropriate position ofthe length of the printing paper P1 or P2 while rotating the rollercutter 41.

Disposed below the roller cutter 41 is a chip collecting box 65 forcollecting chips of the printing paper P1 or P2 formed by the cutting.The chip collecting box 65 is configured so that the operator can slideit out of the housing 6 by pulling its handle 66 and take out the chipscollected in it.

The piece of printing paper P1 or P2 cut by the cutter unit U3 isconveyed to the paper output unit U4 by a pair of conveyance rollers 43engaged against each other. The back printing unit 4 is disposed betweenthe cutter unit U3 and the paper output unit U4. In the back printingunit 4, a serial number or the like is printed on the back (underside)of the printing paper P1 or P2 passing through it.

The paper output unit U4 includes two pairs of output rollers 45 and 46for conveying the piece of printing paper P1 or P2 and delivering it tothe decurling unit U7.

The conveyance rollers 43 and the output rollers 45 and 46 areconfigured to be synchronously driven into rotation by an unshownelectric motor. Furthermore, the later-described conveyance roller 81and decurling roller 82 of the decurling unit U7 are likewise configuredto be driven into rotation by the electric motor (actuator) insynchronism with the conveyance rollers 43 and the output rollers 45 and46. Note that both the conveyance roller 81 and the decurling roller 82need not necessarily be driven into rotation and only one of both(preferably, only the conveyance roller 81) may be driven into rotation.

Furthermore, each pair of conveyance rollers 43 and output rollers 45and 46 are configured to be disengaged one from the other before theleading edge of the printing paper P1 or P2 conveyed by the upstreamconveyance drive roller 24 and print conveyance rollers 33 is pinchedbetween the pair.

Specifically, when the printing paper P1 or P2 is conveyed from theconveyance drive roller 24 and the print conveyance rollers 33 towardsthe pair of conveyance rollers 43, the upper conveyance roller moves upand disengages from the lower conveyance roller before the leading edgeof the printing paper P1 or P2 contacts the pair of conveyance rollers43. Likewise, when the printing paper P1 or P2 having passed through theconveyance rollers 43 is conveyed towards each of the two pairs ofoutput rollers 45 and 46, the upper roller of each pair of outputrollers 45 and 46 moves up and disengages from the lower roller beforethe leading edge of the printing paper P1 or P2 contacts the pair ofoutput rollers. This eliminates inconveniences, such as creases of theprinting paper P1 or P2 formed owing to its leading edge lodging on theconveyance rollers 43 and the output rollers 45 and 46.

Furthermore, after the printing of an image in the print unit U2 andbefore the cutting of the printing paper P1 or P2 in the cutter unit U3,the upper rollers of the pair of conveyance rollers 43 and the pairs ofoutput rollers 45 and 46, which have been moved up, are concurrentlyreturned to their positions of engagement against the lower rollers,thereby pinching the printing paper P1 or P2. This prevents the printingpaper P1 or P2 from being displaced when being cut, which ensuresaccurate paper cutting.

The drying unit U6 is, as shown in FIG. 6, disposed between two pairs ofengageable rollers in the paper output unit U4, i.e., between the pairof upstream output rollers 45 and the pair of downstream output rollers46. The drying unit U6 is configured to suck air into the housing 6through an air inlet 48 formed in the housing 6 above and in thevicinity of the paper output port 47, apply heat to the sucked air andblow out the air as dry air.

The drying unit U6 includes a drying chamber 71 disposed on the paperconveyance path of the printing paper P1 or P2, a dryer 72 for supplyingdry air to the drying chamber 71 and an outside cover 70 for introducingthe air sucked in the housing 6 through the air inlet 48 to the dryer72. The drying chamber 71 is defined by an upper partition wall 71 a anda lower partition wall 71 b that are opposed to each other with theprinting paper P1 or P2 therebetween, and constitutes a retention spacefor retaining dry air blown against the printing paper P1 or P2 from thedryer 72.

The dryer 72 includes a plurality of intake fans 73 disposed in thehousing 6 at laterally spaced intervals to take air from the outsidethrough the air inlet 48 of the housing 6 into the dryer 72, a heater 74for heating the air taken in by the intake fans 73, and an exhaustnozzle 75, disposed at the lower end of the dryer 72, for blowing dryair heated by the heater 74 therethrough to the printing paper P1 or P2.The exhaust nozzle 75 opens at the bottom of the dryer 72 and downstreamin the direction of paper conveyance and is configured to blow dry airdown and downstream in the direction of paper conveyance. The dry air isused to dry ink adhering to the printing surface of the printing paperP1 or P2 in the printing part 2.

The outside cover 70 is disposed above the paper output port 47 of thehousing 6 and configured to allow air sucked in the housing 6 throughthe air inlet 48 to flow through a flow space 76 located in the outsidecover 70 and introduce the air to the intake fans 73. The outside cover70 has an openable and closable rear door formed in the surface thereof.Since such a drying unit U6 is provided, the blow of dry air promotesthe drying of ink ejected from the print head H to the printing paper P1or P2 even if the ink on the printed piece of paper is not yet dried.

—Decurling Unit—

Next, a description is given of the structure of the decurling unit U7.As shown in FIG. 6, the decurling unit U7 (i.e., the later-describedroller pair composed of a conveyance roller 81 and a decurling roller82) is disposed at the terminal end of the paper conveyance pathprovided in the housing 6 of the printer body 90 and in the vicinity ofthe paper output port 47 in the housing 6 (on the downstream side of thedryer 72) and configured to output a piece of printing paper P1 or P2,which has been conveyed to the terminal end of the conveyance path, fromthe terminal end through the paper output port 47 to the paper outputtray 5. The paper output tray 5 is disposed below the terminal end ofthe paper conveyance path (the paper output port 47), whereby a leveldifference is produced between the paper output tray 5 and the terminalend of the paper conveyance path.

In addition, the decurling unit U7 has the function of performing adecurling process of correcting the curl of a paper web P2 that is acore set formed by rolling the paper web P2 around the core (i.e., acurl of the paper web P2 curving with the back inside), and includes aroller pair composed of a conveyance roller 81 (corresponding to a firstroller) and a decurling roller 82 (corresponding to a second roller) anda position changing element 83 for changing the relative position of thedecurling roller 82 to the conveyance roller 81. Furthermore, a freeroller 80 is disposed upstream of the conveyance roller 81 to rotate inconjunction with the movement of the piece of printing paper P1 or P2being conveyed.

The conveyance roller 81 is, as shown in FIGS. 7 and 8, composed of aroller shaft 81 a extending in the width direction of the printing paperP1 or P2 and a plurality of roller bodies 81 b, 81 b, . . . arranged atspaced intervals in the axial direction of the roller shaft 81 a.

Disposed on the downstream side of the conveyance roller 81 is a guidemember 92 for smoothly feeding the piece of printing paper P1 or P2output from the conveyance roller 81 towards the paper output tray 5while guiding the trailing edge thereof to prevent it from being caughtby the conveyance roller 81. The guide member 92 includes a pair oflaterally arranged guide plates 92 b and 92 b, extending in the axialdirection of the conveyance roller 81 to cover the lower edge of theconveyance roller 81, for guiding the piece of printing paper P1 or P2to the paper output tray 5, and projections 92 a, 92 a, projecting fromthe upper edge of the guide plates 92 b and 92 b to come between eachadjacent roller bodies 81 b and 81 b, for guiding the trailing edge ofthe piece of printing paper P1 or P2 against being caught between eachadjacent roller bodies 81 b and 81 b.

The decurling roller 82 has a smaller diameter than the conveyanceroller 81, extends continuously in the width direction of the printingpaper P1 or P2 and is disposed travelably substantially along the rollersurface of the conveyance roller 81 (the outer peripheries of the rollerbodies 81 b). As described later, a decurling position, a conveyanceposition and a pinch release position are set on the traveling path ofthe decurling roller 82. The decurling roller 82 is changed to theseplural positions.

Specifically, a shaft end of the decurling roller 82 is rotatablyattached to a lever 84. The lever 84 includes an attachment part 84 ahaving a general shape of the letter C to surround the upstream side ofthe conveyance roller 81when viewed in the axial direction of the rollershaft 81 a (in the width direction of the printing paper P1 or P2) andan abutment part 84 b extending upstream and obliquely downward from theupstream side of the lower end of the attachment part 84 a. Thedecurling roller 82 is rotatably attached to the upper distal end of thegenerally C-shaped attachment part 84 a, while a lever shaft 85 isattached to the lower distal end thereof. The decurling roller 82 isconfigured to circularly move substantially along the roller surface ofthe conveyance roller 81 by pivotally moving the lever 84 about thelever shaft 85.

Furthermore, a bias spring 86 is anchored to the abutment part 84 b ofthe lever 84 and an attachment bracket 91 disposed to the upstream sideof the free roller 80 to urge the lever 84 towards rotatingcounterclockwise in FIG. 6 and putting the decurling roller 82 into thelater-described pinch release position.

Disposed on the upstream side of the lever 84 is the position changingelement 83 for pressing the lever 84 while abutting on the abutment part84 b to rotate the lever 84 clockwise against the urging force of thebias spring 86. The position changing element 83 includes a body 83 apivotable about a pivot shaft 83 c extending in the width direction ofthe printing paper P1 or P2 and a roller 83 b rotatably attached to theupper end of the body 83 a and capable of abutting on the abutment part84 b. The body 83 a is configured to be pivotally moved about the pivotshaft 83 c by an unshown pulse motor.

Furthermore, the position changing element 83 is configured to changethe relative position of the decurling roller 82 to the conveyanceroller 81 by changing its angle of rotation while allowing its roller 83b to abut on the abutment part 84 b of the lever 84.

More specifically, as shown in FIG. 9, when the roller 83 b of theposition changing element 83 is not allowed to abut on the abutment part84 b of the lever 84, the lever 84 is positioned in the pinch releaseposition, which is the leftmost position (the most downstream position),by the urging force of the bias spring 86. In the pinch releaseposition, the decurling roller 82 is out of touch with the conveyanceroller 81 on the opposite side of the paper conveyance path to theconveyance roller 81 (above the conveyance roller 81), whereby a givenclearance H (larger than the thickness of the printing paper P1 or P2)is created between the conveyance roller 81 and the decurling roller 82and the pinch of the printing paper P1 or P2 (roller engagement) isreleased. Thus, in the pinch release position, the printing paper P1 orP2 cannot be conveyed. Furthermore, in the pinch release position, theaxis of rotation of the decurling roller 82 is located closer to thepaper output side than (downstream from) the axis of rotation of theconveyance roller 81. A detection lug 87 is attached to the body 83 a ofthe position changing element 83. When the detection lug 87 deviates tothe left from a transmission sensor 88 as shown in FIG. 9, it isdetected that the decurling roller 82 is positioned in the pinch releaseposition.

With the above configuration, the pinch of the printing paper P1 or P2between the conveyance roller 81 and the decurling roller 82 can bereleased. For example, when the paper conveyance is temporarily stoppedowing to intermittent paper conveyance in order to form an image on thepaper, the pressing of the decurling roller 82 against a paper web P2 isreleased by moving the decurling roller 82 in decurling process from thelater-described decurling position to the pinch release position. Thus,an inconvenience can be eliminated that an indentation of the decurlingroller 82 is left on the paper web P2. This prevents deterioration ofprinting quality due to the indentation.

Next, as shown in FIG. 10, the body 83 a of the position changingelement 83 is pivotally moved counterclockwise to press the roller 83 bagainst the abutment part 84 b of the lever 84 until the transmissionsensor 88 detects the detection lug 87. Thus, the lever 84 is pivotallymoved clockwise against the urging force of the bias spring 86 toposition the decurling roller 82 in the conveyance position in which thedecurling process is disabled and a paper sheet P1 is conveyed. In theconveyance position, the paper sheet P1 is pinched between theconveyance roller 81 and the decurling roller 82 and both the rollers 81and 82 are driven into rotation, whereby the paper sheet P1 is deliveredto the paper output tray 5. Furthermore, in the conveyance position, thedecurling roller 82 is positioned slightly upstream from the conveyanceroller 81. In other words, the axis of rotation of the conveyance roller81 is located closer to the paper output side than the axis of rotationof the decurling roller 82. Furthermore, in the conveyance position, thepaper sheet P1 is never bent along the roller surface of the decurlingroller 82. Even if a paper web P2 is conveyed in the conveyanceposition, the paper web P2 is not bent along the roller surface of thedecurling roller 82 and, therefore, it cannot be decurled.

Since the decurling roller 82 is positioned slightly upstream from theconveyance roller 81, a greater clearance is created between both theconveyance roller 81 and the decurling roller 82 than the case whereboth the rollers 81 and 82 are vertically juxtaposed with respect to thepaper conveyance direction (but it is smaller than the thickness of thepaper sheet P1). Thus, the pinching force of the rollers 81 and 82against the paper sheet P1 can be reduced to reduce the load applied tothe paper sheet P1. Specifically, the paper sheet P1 is conveyed in aslightly sagging state. Therefore, even if the pinching force isreduced, the restoring force of the paper sheet P1 towards stretchingstraight and the frictional force between the paper sheet P1 and thepair of rollers 81 and 82 provide smooth conveyance of the paper sheetP1 using the resilience of the paper sheet P1.

In the conveyance position, the clearance between both the rollers 81and 82 is smaller than the thickness of the paper sheet P1. However,when both the rollers 81 and 82 pinch the paper sheet P1, at least theroller surface of the conveyance roller 81 deforms so that the clearancebetween both the rollers 81 and 82 becomes equal to the thickness of thepaper sheet P1.

Then, as shown in FIG. 11, the body 83 a of the position changingelement 83 is further pivotally moved counterclockwise to press theroller 83 b against the abutment part 84 b until the detection lug 87deviates to the right from the transmission sensor 88 and is notdetected by it. Thus, the decurling roller 82 is positioned in thedecurling position in which the decurling process is enabled and a pieceof paper web P2 is conveyed. In the decurling position, the axis ofrotation of the decurling roller 82 is located upstream from the axis ofrotation of the conveyance roller 81 and the decurling roller 82 movestowards the conveyance roller 81 (below) beyond the paper conveyancepath. Thus, the decurling roller 82 presses down the piece of paper webP2 to bend it along the roller surface of the decurling roller 82 withits printing surface inside, thereby decurling the piece of paper webP2. Furthermore, in the same manner as in the conveyance position, thepiece of paper web P2 is pinched between the conveyance roller 81 andthe decurling roller 82 and both the rollers 81 and 82 are driven intorotation, whereby the piece of paper web P2 is delivered to the paperoutput tray 5. In the decurling position, like in the conveyanceposition, the axis of rotation of the conveyance roller 81 is locatedcloser to the paper output side than the axis of rotation of thedecurling roller 82. However, in the decurling position, the distancebetween both the axes of rotation along the conveyance direction islarger than that in the conveyance position.

In this case, the clearance between the decurling roller 82 and theconveyance roller 81 when the decurling roller 82 is in the decurlingposition is set to be larger than that when the decurling roller 82 isin the conveyance position. Specifically, the clearance between thedecurling roller 82 and the conveyance roller 81 is set to be largerthan the thickness of the paper web P2 when the decurling roller 82 isin the decurling position, while the clearance is set to be smaller thanthe thickness of the paper web P2 (and the thickness of the paper sheetP1) when the decurling roller 82 is in the conveyance position.

Thus, in moving the decurling roller 82 from the conveyance position tothe decurling position, the clearance is gradually changed, whichprevents a strong pressing force from rapidly acting on the restoringforce of the piece of paper web P2 towards stretching straight andminimizes damage to the piece of paper web P2.

A plurality of decurling positions are set substantially along theroller surface of the conveyance roller 81 (and shown in the imaginarylines in FIG. 11). In an example shown in FIG. 11, the position of thedecurling roller 82 shown in the solid line is a reference decurlingposition, the position of the decurling roller 82 moved clockwise fromthe reference position is a strong decurling position where thedecurling force of the decurling roller 82 (the pressing force thereofagainst the paper web P2) is strong, the position of the decurlingroller 82 moved counterclockwise from the reference position is a weakdecurling position where the decurling force is weak, and the positionof the decurling roller 82 further moved counterclockwise from the weakdecurling position is a weakest decurling position where the decurlingforce is weakest. The position changing element 83 adjusts the strengthof the decurling force to the paper web P2 by moving the decurlingroller 82 among the plural decurling positions from the weakest to thestrong decurling position.

With the above configuration, an appropriate decurling force to theshape of a curl of the piece of paper web P2 can be applied to the pieceof paper web P2. Specifically, part of the paper web P2 in the vicinityof the core around which the paper web P2 is rolled has a small radiusof curvature and is therefore strongly curled, while part of the paperweb P2 in the vicinity of the outer periphery thereof has a large radiusof curvature and is therefore weakly curled. To cope with this, thestrength of the decurling force is adjusted according to the amount ofuse of the rolled paper web P2 contained in the paper roll containingpart 1. Thus, the curl of each piece of the paper web P2 can becorrected with an optimum decurling force. Specifically, at an initialstage of use, the paper web P2 is determined to be weakly curled and,therefore, the decurling roller 82 is set to the weakest decurlingposition. At a middle stage of use, the decurling roller 82 is set tothe weak decurling position. At a late stage of use, the decurlingroller 82 is set to the strong decurling position.

Furthermore, when the length of a piece of paper web P2 cut in a givenlength by the cutter unit U3 is larger than a predetermined value, thedecurling force to the cut piece of paper web P2 may be set to bestronger than when the length of a cut piece of paper web P2 is equal toor smaller than the predetermined value. In other words, such a long cutpiece of paper web P2 is determined to be more flexible and morestrongly curled and, therefore, a strong decurling force is applied toit. Alternatively, the decurling force applied to the piece of paper webP2 may be set to be larger as the piece of paper web P2 becomes longer.

Furthermore, the decurling force applied to the piece of paper web P2may be adjusted according to the material of the paper web P2. In thiscase, an appropriate decurling force with which the piece of paper webP2 can be easy to decurl is applied to the piece of paper web P2according to its material, such as by setting a strong decurling forcefor the paper web P2 made of a hard material having a strong elasticity.

Alternatively, for example, information on the date of production of thepaper web P2 may be stored in a memory, such as an IC chip, provided inthe core for the paper web P2 and the strength of the decurling forceapplied to each cut piece of the paper web P2 may be adjusted accordingto the number of days elapsed from the data of production by reading theinformation on the date of production. Specifically, if the number ofdays elapsed from the date of production, having been read from thememory for the paper web P2, is over a predetermined number of days, thecut piece of paper web P2 is determined to be strongly curled and thedecurling force is set to be strong.

In this first example embodiment, the decurling position or theconveyance position corresponds to the first position on the travelingpath of the decurling roller 82 and the pinch release positioncorresponds to the second position located on the traveling path of thedecurling roller 82 and closer to the paper output side than the firstposition. Furthermore, the position changing element 83 and the lever 84constitute a roller position changing mechanism for switching thedecurling roller 82 between the first position and the second position.

As shown in FIG. 6, the under surface of a lower partition wall 71 bdefining part of the drying chamber 71 of the drying unit U6 has adetection sensor 93 provided on a downstream part thereof to detect theleading edge and trailing edge of a piece of printing paper P1 or P2.When the detection sensor 93 detects the leading edge of the piece ofprinting paper P1 or P2, the piece of printing paper P1 or P2 isconveyed a predetermined length from the point in time of detectionuntil the leading edge of the piece of printing paper P1 or P2 reaches apoint corresponding to the conveyance roller 81 and, then, the decurlingroller 82 of the decurling unit U7 is moved from the pinch releaseposition to the decurling position or conveyance position. Specifically,the decurling roller 82 stands by at the pinch release position asdescribed later, so that the conveyance roller 81 and the decurlingroller 82 can smoothly pinch the piece of printing paper P1 or P2 whenthe piece of printing paper P1 or P2 is transferred from the paperoutput unit U4 to the decurling unit U7. This eliminates inconveniences,such as creases of the piece of printing paper P1 or P2 formed owing toits leading edge lodging on the conveyance roller 81 and the decurlingroller 82.

On the other hand, when the detection sensor 93 detects the trailingedge of the piece of printing paper P1 or P2, the piece of printingpaper P1 or P2 is conveyed a predetermined length from the point in timeof detection until the trailing edge of the piece of printing paper P1or P2 reaches a point between the free roller 80 and the conveyanceroller 81 and, then, the decurling roller 82 of the decurling unit U7 ismoved from the decurling position or conveyance position to the pinchrelease position. In other words, when the trailing edge of the piece ofprinting paper P1 or P2 is sent out to the paper output tray 5 in thecourse of output of the piece of printing paper P1 or P2 to the paperoutput tray 5 by means of the conveyance roller 81 and the decurlingroller 82 being in the decurling position or the conveyance position,the decurling roller 82 is switched from the decurling position or theconveyance position to the pinch release position.

Thus, in conjunction with movement of the decurling roller 82 from thedecurling position or the conveyance position to the pinch releaseposition, the trailing edge of the piece of printing paper P1 or P2 ismoved at a stroke to the paper output tray 5. Therefore, the outputspeed of the piece of printing paper P1 or P2 increases, which providessmooth transfer of the piece of printing paper P1 or P2 to the paperoutput tray 5 and stabilizes the placement point of pieces of printingpaper P1 or P2 on the paper output tray 5. Specifically, a leveldifference exists between the paper output tray 5 and the terminal endof the paper conveyance path and, therefore, the leading edge of thepiece of printing paper P1 or P2 is likely to sag by gravity and is sentout while sliding on the top surface of the paper output tray 5 or thetop surface of the piece of printing paper P1 or P2 already placed onit. In this case, after the trailing edge of the piece of printing paperP1 or P2 is output, the paper stop point, i.e., the paper placementpoint, is not fixed owing to the frictional resistance acting on theleading edge thereof. To cope with this, if the output speed of thepiece of printing paper P1 or P2 is increased in sending out thetrailing edge of the piece of printing paper P1 or P2, the paperplacement point can be stabilized. On the other hand, the output speedof the piece of printing paper P1 or P2 is decreased in sending out thepart thereof other than the trailing edge. Thus, the ink adhering to theprinting surface of the piece of printing paper P1 or P2 can becertainly dried by the dryer 72 of the drying unit U6. Then, when theoutput of the piece of printing paper P1 or P2 is completed, thedecurling roller 82 is positioned in the pinch release position.Therefore, the decurling roller 82 can stand by as it is until theleading edge of the next piece of printing paper P1 or P2 comes to thedecurling roller 82. This eliminates the need to bother to change thedecurling roller 82 to the pinch release position in transferring thenext piece of printing paper P1 or P2.

Furthermore, when the trailing edge of the piece of printing paper P1 orP2 comes between the free roller 80 and the conveyance roller 81, i.e.,when the trailing edge of the piece of printing paper P1 or P2 is sentout to the paper output tray 5 in the course of output of the piece ofprinting paper P1 or P2 to the paper output tray 5 by means of theconveyance roller 81 and the decurling roller 82 being in the decurlingposition or the conveyance position, the rotational speed of theelectric motor driving the conveyance roller 81 and the decurling roller82 is increased in addition to movement of the decurling roller 82 tothe pinch release position. As a result, the rotational driving speed ofthe conveyance roller 81 and the decurling roller 82 is changed to theirhigher side, whereby the placement point of pieces of printing paper P1or P2 on the paper output tray 5 can be further stabilized.

Furthermore, since the decurling unit U7 is disposed downstream of thedryer 72 to decurl the piece of paper web P2 just after being dried bythe dryer 72, this is advantageous in appropriately correcting the curlof the piece of paper web P2. Specifically, the piece of paper web P2heated by dry air from the dryer 72 is very likely to be deformed.Therefore, if the piece of paper web P2 in this state is decurled by thedecurling unit U7, a higher decurling effect can be obtained than whenthe piece of paper web P2 is not heated.

As described so far, when a rolled paper web P2 is conveyed, thedecurling unit U7 corrects the curl of each piece of the paper web P2 bymoving the decurling roller 82 to the decurling position and subjectingthe piece of paper web P2 to the decurling process. On the other hand,when a paper sheet P1 is conveyed, the decurling unit U7 conveys thepaper sheet P1 to the paper output tray 6 without subjecting it to thedecurling process by moving the decurling roller 82 to the conveyanceposition. In this manner, the decurling unit U7 selects whether or notto perform the decurling process depending upon the type of printingpaper P1 or P2 being conveyed. Therefore, it can be avoided that thepaper sheet P1 originally having no curl is subjected to the decurlingprocess and thereby curled. As a result, the decurling unit U7 canappropriately handle a piece of rolled printing paper P2 and a sheet ofprinting paper P1.

Furthermore, when the trailing edge of the piece of printing paper P1 orP2 is sent out to the paper output tray 5, the piece of printing paperP1 or P2 is accelerated in the paper output direction by changing thedecurling roller 82 of the decurling unit U7 from the decurling positionor the conveyance position to the pinch release position. Thisstabilizes the placement point of pieces of printing paper P1 or P2 onthe paper output tray 5.

Second Example Embodiment

FIG. 12 is a perspective view showing the structure of an inkjet printeraccording to a second example embodiment. This example embodiment isdifferent from the first example embodiment in that a conveyance unit100 and an collection unit 110 are provided instead of the paper outputtray 5. Therefore, the same parts are identified by the same referencenumerals as in the first example embodiment and a description is givenonly of different points.

As shown in FIGS. 12 and 13, the inkjet printer A includes a printerbody 90, a conveyance unit 100 disposed downstream of the printer body90, and a collection unit 110 disposed downstream of the conveyance unit100 in the direction of paper conveyance. The printer body 90 hassubstantially the same structure as described in the first exampleembodiment and, therefore, a description thereof is not given.

The conveyance unit 100 constitutes a paper placement part for receivingpieces of printing paper P1 or P2 output through the paper output port47 in the housing 6 of the printer body 90 and placing them thereon andincludes a conveying belt 101 for conveying pieces of printing paper P1or P2 placed thereon downstream like a belt conveyer, a drive roller 102for driving the conveying belt 101 and a large-sized tray 104 disposedupstream of the conveying belt 101 in the direction of paper conveyance.“Downstream of the conveyance unit 100 in the direction of paperconveyance” means to the right of the housing 6 (towards the collectionunit 110).

The region of the conveying belt 101 corresponding to the paper outputport 47 in the housing 6 is set to a placement region R where a piece ofprinting paper P1 or P2 just after being output through the paper outputport 47 is received (strictly, this placement region R corresponds tothe paper placement part). The placement region R of the conveying belt101 is, like the paper output tray 5 in the first example embodiment,also disposed below the terminal end of the paper conveyance pathprovided in the interior of the housing 6 of the printer body 90 (belowthe paper output tray 47). Furthermore, the conveyance unit 100 isconfigured to control the movement of the conveying belt 101 to allowthe already placed piece of printing paper P1 or P2 to leave theplacement region R before the next piece of printing paper P1 or P2 tobe output through the paper output port 47 in the housing 6 is placed onthe placement region R.

Thus, pieces of printing paper P1 or P2 can be prevented from beingstacked one after another, which prevents inconveniences, such as aphenomenon that ink on each printed piece of printing paper P1 or P2 isnot uniformly dried to cause color shading of printed images.

The control on the movement of the conveying belt 101 is implemented byadjusting the speed of paper conveyance so that when the piece ofprinting paper P1 or P2 already placed on the placement region R leavesthe placement region R, the next piece of printing paper P1 or P2 isoutput. Furthermore, instead of continuing to drive the conveying belt101 at a constant speed, pieces of printing paper P1 or P2 may beintermittently conveyed so that the piece of printing paper P1 or P2already placed on the placement region R can be conveyed at a stroke tothe outside of the placement region R when the next piece of printingpaper P1 or P2 is conveyed.

In this case, if a piece of printing paper P1 or P2 having a normalprint size, such as L size, is placed on the conveying belt 101, theconveyance unit 100 is controlled to convey the piece of printing paperP1 or P2 to the collection unit 110 disposed downstream thereof in thedirection of paper conveyance. On the other hand, if a piece of printingpaper P1 or P2 having a large size is placed on the conveying belt 101,the conveyance unit 100 is controlled to convey the piece of printingpaper P1 or P2 to the large-sized tray 104 disposed upstream thereof inthe direction of paper conveyance. In this manner, by changing thedirection of paper conveyance according to the size of piece of printingpaper P1 or P2, pieces of printing paper P1 or P2 can be conveyed toappropriate accommodation sites for each paper size.

The collection unit 110 is disposed downstream of the conveyance unit100 in the direction of paper conveyance and configured to collectpieces of printing paper P1 or P2 conveyed from the conveyance unit 100.The collection unit 110 includes a collecting body 111, a plurality ofcollecting plates 112, arranged at spaced intervals in the collectingbody 111, for placing pieces of printing paper P1 or P2 conveyed fromthe conveyance unit 100 thereon, and a collecting belt 113 for conveyingthe plurality of collecting plates 112 towards the rear of the housing 6like a belt conveyer.

Each collecting plate 112 stands by at a transfer point for pieces ofprinting paper P1 or P2 located downstream of the conveying belt 101 sothat the plate surface is horizontal and substantially flush with thesurface of the conveying belt 101. Then, when a predetermined number ofpieces of printing paper P1 or P2 are stacked on the collecting plate112 according to the print order, the collecting plate 112 is conveyedto the rear of the housing 6 by the collecting belt 113 before the nextpiece of printing paper P1 or P2 is conveyed according to the next printorder. Then, the surface of the collecting plate 112 having been heldhorizontal stands up in the course of conveyance of the collecting belt113 to function as a partition plate for partitioning pieces of printingpaper P1 or P2 for each print order.

In this case, the conveyance unit 100 controls the movement of theconveying belt 101 so that when the piece of printing paper P1 or P2 istransferred from the conveying belt 101 to each collecting plate 112 ofthe collection unit 110, the speed of conveyance of the piece ofprinting paper P1 or P2 reaches a predetermined speed or more.Specifically, a clearance is left between the conveying belt 101 and thecollecting plate 112 facing it. Therefore, if the speed of paperconveyance of the conveying belt 101 is too late, the edge of the pieceof printing paper P1 or P2 may drop in the clearance, leading to failureof smooth paper transfer or failure of paper transfer. To avoid this,the speed of paper conveyance of the conveying belt 101 is controlled tobe a speed at which the piece of printing paper P1 or P2 can be stablytransferred, thereby ensuring the transfer of the piece of printingpaper P1 or P2.

In this manner, by partitioning pieces of printing paper P1 or P2 withthe collecting plates 112 for each print order, the pieces of printingpaper P1 or P2 can be easily set in each order. Furthermore, since thenumber of pieces of printing paper P1 or P2 accommodated can beincreased, the frequency with which the worker picks up pieces ofprinting paper P1 or P2 after being printed can be reduced, whichincreases the working efficiency.

Also in the second example embodiment, like the first exampleembodiment, a decurling unit U7 (a roller pair composed of a conveyanceroller 81 and a decurling roller 82) is disposed at the terminal end ofthe paper conveyance path provided in the interior of the housing 6 ofthe printer body 90. The decurling unit U7 outputs pieces of printingpaper P1 or P2 through the paper output port 47 in the housing 6 to theplacement region R of the conveying belt 101. If, as in this case, thepaper placement part is a conveying belt 101, the level differencebetween the paper placement part and the terminal end of the paperconveyance path (the paper output port 47) is generally larger thanwhere the paper placement part is a paper output tray 5. Therefore, thefrictional resistance acting on the leading edge of the piece ofprinting paper P1 or P2 is greater and the placement point of pieces ofprinting paper P1 or P2 is likely to vary. However, this second exampleembodiment is, like the first example embodiment, also configured sothat when the trailing edge of the piece of printing paper P1 or P2reaches between the free roller 80 and the conveyance roller 81, thedecurling roller 82 of the decurling unit U7 moves from the decurlingposition or the conveyance position to the pinch release position andthe rotational driving speed of the conveyance roller 81 and thedecurling roller 82 is changed to their higher side. Thus, the piece ofprinting paper P1 or P2 can be accelerated in the paper output directionto stabilize the placement point of pieces of printing paper P1 or P2 onthe placement region R. As a result, the transfer of pieces of printingpaper P1 or P2 from the conveying belt 101 to each collecting plate 112of the collection unit 110 can be certainly carried out.

Although in the above example embodiments the second position is thepinch release position where the pinch of the printing paper P1 or P2between the conveyance roller 81 and the decurling roller 82 isreleased, the second position may be anywhere closer to the paper outputside than the first position unless the piece of printing paper P1 or P2can be accelerated in the paper output direction by the movement of thedecurling roller 82 from the first position to the second position ormay be a location where the piece of printing paper P1 or P2 can bepinched and conveyed.

The relationships between the axes of rotation of the first and secondrollers in the first and second positions are not limited to those inthe above example embodiments.

Furthermore, when the trailing edge of the piece of printing paper P1 orP2 comes between the free roller 80 and the conveyance roller 81, therotational driving speed of the conveyance roller 81 and the decurlingroller 82 may not necessarily be changed to higher side.

The present invention is not limited to the paper output mechanismdisposed in the interior of the printer body 90 of the inkjet printer Aand can be applied to any paper output mechanism, disposed in a deviceincluding a paper conveyance path, for outputting paper to the outsideof the device. Furthermore, the present invention is not limited topaper output mechanisms for outputting paper to the outside and can bealso applied, for example, to a paper output mechanism for outputtingpaper from the terminal end of a paper conveyance path in a firstprocessing section in the interior of the device to a paper placementpart of a second processing section disposed below the terminal end ofthe paper conveyance path in the first processing section.

1. A paper output mechanism, disposed at the terminal end of a paperconveyance path, for outputting a piece of paper conveyed to theterminal end of the paper conveyance path from the terminal end thereofto a paper placement part disposed below the terminal end of the paperconveyance path, the paper output mechanism comprising: a roller paircomposed of a first roller and a second roller travelable around thefirst roller and configured, when the second roller is in a firstposition on a traveling path of the second roller, to output the pieceof paper to the paper placement part by pinching the piece of paperbetween the first and second rollers and driving at least one of thefirst and second rollers into rotation with an actuator; and a rollerposition changing mechanism for switching the second roller between thefirst position and a second position located on the traveling path ofthe second roller and closer to the paper output side than the firstposition, the roller position changing mechanism being configured, whenthe first roller and the second roller in the first position send outthe trailing edge of the piece of paper to the paper placement part inthe course of output of the piece of paper to the paper placement part,to change the second roller from the first position to the secondposition.
 2. The paper output mechanism of claim 1, wherein the firstposition is a position in which the axis of rotation of the first rolleris located closer to the paper output side than the axis of rotation ofthe second roller, and the second position is a position in which theaxis of rotation of the second roller is located closer to the paperoutput side than the axis of rotation of the first roller and the pinchof the piece of paper between the first and second rollers is released.3. The paper output mechanism of claim 1, wherein when the first rollerand the second roller in the first position send out the trailing edgeof the piece of paper to the paper placement part in the course ofoutput of the piece of paper to the paper placement part, the rotationaldriving speed of the roller driven into rotation by the actuator ischanged to higher side.
 4. The paper output mechanism of claim 1,wherein the roller pair is disposed at the terminal end of the paperconveyance path provided in a printer body and in the vicinity of apaper output port in the printer body.